Pesticides are chemicals used since ancient times to destroy or control pests. Although the primary hazard to humans associated with pesticide exposure is acute poisoning, there has been considerable concern surrounding the possibility of pesticide carcinogenicity and other chronic health effects in humans. The pesticides which have generated the greatest concern for possible carcinogenicity include the herbicides (chlorophenoxy acids and chlorophenols), heavy metals (especially arsenicals), petroleum products (polyaromatic hydrocarbons), organochlorines, and fumigation agents (EDB, Methyl Bromide). This is important given the huge volume of pesticides now used throughout the world in agriculture, industry and in homes; in addition, there is concern with regards to the environmental and food residue contamination from pesticides which could lead to mass chronic low-level exposure. Under EPA since 1970, the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) has required that persons who buy or use restricted-use pesticides must be certified as competent pesticide applicators or must be directly supervised by a certified applicator. The State of Florida has computerized records of over l6,000 certified pest applicators for over 10 years and paper records for up to 25 years. In addition, as a highly agricultural and tropical state, Florida is a major pesticide user. The proposed study will be retrospective cohort analyses of the cancer incidence and general mortality, with a nested (synthetic) case control study of cancer incidence, among a cohort of the Florida certified pesticide applicators with occupational pesticide exposure. Cancer incidence since 1980 will be obtained by limiting the data from the pest applicator licenses with the Florida Cancer Data System (FCDS). Mortality information will be obtained through the Florida Vital Statistics Death Linkage. In a nested (synthetic) case control study, exposure and relevant risk behavior data will be sought through the distribution of a questionnaire to selected cases of incident cases of cancer and a random sample of matched applicators as controls. Information concerning specific pesticide use, race/ethnic status, and possible confounding factors (such as tobacco use) will be obtained. Analyses will evaluate total cancer incidence and specific cancer incidences compared to age and sex adjusted state and national rates. In addition, risks for specific cancers associated with pesticide exposure will be evaluated, controlling for confounding variables such as tobacco use and using an internal cohort control group. Finally, cause specific mortality and cancer incidence experience of this cohort with national and internal comparisons will be evaluated. Because the greatest exposures to pesticides occur in the occupational setting, this study should adds to the body of knowledge concerned with pesticides and their health effects in humans. Results from the study (i.e. specific cancer and other mortality rates, protective equipment use, and other risk factors) can be incorporated into existing mandatory educational programs of the Florida Department of Agriculture Bureau of Pesticides to prevent future illness in this and similar workforces.